1. Field of the Invention
The present invention relates to a pipe joint, which couples to the relevant radiator a radiator hose for returning coolant water from an internal combustion engine to a radiator.
2. Description of the Related Art
Coolant water, which has been heated by heat of an engine in an automobile or the like, is conveyed to a radiator by way of a radiator hose at a return side, and cooled in the radiator by natural ventilation and fan. Thereafter, the coolant water is supplied again to the engine by way of a radiator hose at a supply side.
Generally, the radiator hose at the return side is coupled to an upper portion of the radiator, and the radiator hose at the supply side is coupled to a lower portion of the radiator. The radiator is separately provided with a coolant water injection port equipped with a radiator cap, in the upper portion thereof. A connecting pipe for connecting a tube, which is coupled to a reservoir tank, is fitted to this coolant water injection port.
As to such piping system of the radiator, JP-A-2001-241882 discloses the following radiator for a vehicle for cooling coolant water for an on-vehicle engine. The radiator includes a plurality of tubes, a header tank, a water injection port. The water coolant flows through the plurality of tubes. The header tank is disposed at both ends of a plurality of the tubes in a longitudinal direction thereof so as to be communicated with the tubes. The water injection port is connected to the header tank. The water injection portion is shifted in position from the header tank in a back and forth direction of the vehicle. The water injection port is engaged with and fixed to the header tank by first locking means, which can be elastically deformed. The water injection port is water-tightly connected to the header tank by means of a first seal member having a ring-like shape, which can be elastically deformed. The plural tubes are made of aluminum, and a tank main body such as the header tank is made of resin. JP-A-2001-241882 further discloses that the tank main body may be made of metal such as aluminum.
By the way, as material for the radiator, brass has been mainly employed in the past, but recently, many radiators have come to be made of aluminum as disclosed in JP-A-2001-241882. Aluminum has excellent rigidity and pressure resistance by nature as compared with brass, and has a great advantage in its light weight. Although brass is more excellent in heat conductivity than aluminum, it would be possible to cure this deficiency by increasing a wall thickness in case where aluminum is employed, and strength of a whole structure can be enhanced, while reducing weight. In recent years, such a radiator that the whole body thereof has been made of aluminum is becoming to be utilized.